v5.6.4

Patch Changes

• 87c1f3c: fix: reject __proto__ keys in malformed Object wrapper payloads

  This validates the "Object" parse path and throws when the wrapped value has an own __proto__ key.

• 40f1db1: fix: ensure sparse array indices are integers

• 87c1f3c: fix: disallow __proto__ keys in null-prototype object parsing

  This disallows __proto__ keys in the "null" parse path so null-prototype object hydration cannot carry that key through parse/unflatten.